You can...
Swing firmly and hit the outside of the ball, imparting as much sidespin as topspin.
Change your grip, or use the one you got, and slice the ball, using some amount of sidespin.
Set a firm body and leg, short backswing and controlled forwards swing, stroke thru the ball with a blocking, almost flat stroke.
Try the 3, use what works best for you.

Are you talking about all low forehands in general or specific ones (close to net, mid court, baseline)?
What's the outcome when you mess up your low forehand shots? Frame? Goes into net? Long? Please go into detail. This way we can tell what you are doing wrong and try and give tips or recommendations.

As for what safe shots, I'd recommend deep top spin cross court. Net is lower, court geometry, and shorter distance to recover.

If that low forehand is short i'd go DTL and come to net.

Shot selection also depends on where your opponent is. If he hits a ball to my low forehand and comes in, i'm not going to aim deep cross court because it'd just set him up for a perfect volley. My options would be (1) short cross court shot to pass him (2) pass him down the line (5) go right at him with a short top spin shot so he has to hit a low volley or (4) lob him.

Hitting those low forehands you have to make sure your upper body and lower body are in sync. If you are reaching for that ball you better have your lower body counteracting the reach so you stay in balanace. Bending at your knees like those low volleys help.

Are you talking about all low forehands in general or specific ones (close to net, mid court, baseline)?
What's the outcome when you mess up your low forehand shots? Frame? Goes into net? Long? Please go into detail. This way we can tell what you are doing wrong and try and give tips or recommendations.

As for what safe shots, I'd recommend deep top spin cross court. Net is lower, court geometry, and shorter distance to recover.

If that low forehand is short i'd go DTL and come to net.

Shot selection also depends on where your opponent is. If he hits a ball to my low forehand and comes in, i'm not going to aim deep cross court because it'd just set him up for a perfect volley. My options would be (1) short cross court shot to pass him (2) pass him down the line (5) go right at him with a short top spin shot so he has to hit a low volley or (4) lob him.

Hitting those low forehands you have to make sure your upper body and lower body are in sync. If you are reaching for that ball you better have your lower body counteracting the reach so you stay in balanace. Bending at your knees like those low volleys help.

If you are going in a complete opposite direction i think some of the fundementals need to be worked on. Maybe you are getting there too late and contacting late which would change the direction to down the line.

How are your top spin shots? Another thing for lower shots is you should be closer to them rather than further. Your arm is connected to your body at the shoulder so naturally you will have less reach as the impact point moves lower. Therefore try getting close to that ball, not too close where you are crowding yourself but you shouldn't have to strech to hit the ball, as you will lose power and control.

I'd just work on top spin shots by rallying half court to get fundamentals down pat.

Hard to be specific without knowing exactly how you are dealing with those low balls but in general low balls must be hit with more topspin component than hitting through component compared to normal hitting zone balls. This means you have to orient your body so you can lift your arm upward more effectively than swinging around the torso. To achieve this you need to place your body more to the side of the contact point (ball) and pull the arm up for topspin. for this reason your footwork become more critical than the normal stroke simply because it is different from the normal footwork that you are used to for the majority of the times. The swing will be more vertical than normal and thus the finish will be higher than normal. It's more of a feel and precision shot (less for the target but more for the intended direction and trajectory of the ball or depth) than a power shot so slow down to get a good feel for the different footwork and swing path and then practice faster swing for more topspin.

Basically, in tennis, you want to strive (as much as possible) to hit each ball the same way. So, with a low ball (how low?) you want to get to the ball in plenty of time to set up- and since the ball is low, you want to bend your knees and get down low, yourself, so you stroke will look and feel much the same as hitting a ball in your comfort zone.

Concentrate on the racket path you need to direct the ball to where you want, then drive through the ball with enough low-to-high motion to generate topspin so you get the ball over the net-- then back down into the opponent's court.

For this sort of thing, practice is the key. Have a friend toss you some low, mid-court balls. Practice getting down and hitting through them firmly and fluidly-- through the ball and low-to-high. Pay attention to the result and adjust as necessary until it becomes second-nature.

3rd option is the safe blocking shot, where you're just using the opponent's pace to get the ball back. You have to solidify your body, set wide legs, and use a short, slow stroke to meet the ball center, not trying to add any topspin or slice action to the ball.

When I try to hit them cross court, my shots are ending up down the line and beyond the baseline at least by few yards

I am so disappointed and don't know what to do.

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If you're trying to hit low balls cross court, try hitting further in front of you at contact.
Some basic tips:
Don't jump (unless you really have to) when trying to hit a low ball, generally keep your feet on the ground.

(Personal Experience) When hitting low balls, at contact, have your racket be somewhat perpendicular to the court, rather than parallel. If you have your racket face pointing down towards the court, you'll have an easier time hitting up/through on the ball, producing topspin.